Over many years, this inventor pursued various implementations of toroidal devices beginning with systems that would have an electronic output (missile nose cone signal transmitters), to very high reduction positioning devices (radar and telescopes), and, lately, to compact, high-torque power XYZ transmissions that can be used in, for example, trucks, automobiles, and marine vessels. Exemplary embodiments of toroidal drive transmissions are disclosed in U.S. Reissue Patent 26,476, issued on Oct. 8, 1968; U.S. Pat. No. 4,297,919, issued on Nov. 3, 1981; U.S. Pat. No. 5,784,923, issued on Jul. 28, 1998; and U.S. Pat. No. 5,863,273, issued on Jan. 26, 1999. The entire teachings of the above documents are incorporated herein by reference.
A transmission of the type described in the above patents is depicted in FIG. 1. The load-sharing elements in this type of transmission comprise rotor units 10, each of which includes a hub 12, a ring 14 rotatably mounted coaxially to the hub, and a plurality of fingers 16 or rotor unit arms extending radially outward from the ring. The fingers are terminated by drive rollers 18. The rotors 10 are mounted via the hubs 12 to a large ring 20, which can be referred to as a yoke, centered on the common rotary axis of the transmission input and output shafts 22 and 24. The drive rollers 18 of radially extending inner fingers 16 of the rotor units 10 engage in the grooves of a worm 26 connected to the input shaft 22, and the ring 20 to which the rotor units 10 are mounted is connected by arms 28 to the output shaft 24.
The outer fingers 16 of the rotor units 10 engage in grooves or races 32 inscribed in the interior of a transmission housing 34. When the drive worm 26 is rotated by the input shaft 22, the various rotor units 10 are caused to rotate about their respective hubs 12. Since the rotors 10 also engage in the stator races 32, rotation of those rotors 10 causes the rotors to advance along the races which, in turn, causes the ring 20 to which the rotor units are attached to precess about the rotary axis of the transmission. Since the ring 20 is connected to the output shaft by arms 28, when the ring 20 rotates, so does the output shaft 24.